2 cups all-purpose flour
2 tsp baking powder
1/2 tsp baking soda
1/2 tsp ground nutmeg
1/2 tsp salt
8 Tbsp unsalted butter, cold & cut
1 cup raisins
2 Tbsp granulated sugar
1 large egg yolk
3/4 cup buttermilk or plain yogurt
1 large egg white
Heat oven to 375 F. Put flour, baking powder, baking soda, nutmeg, and salt into a large bowl; stir to mix well. Add butter and cut it with a pastry blender or rub in your fingers, until the mixture looks like fine granules. Add raisins and sugar; toss to distribute evenly.
Add egg yolk to buttermilk in a measuring cup and whisk with a fork to blend. Pour over the flour mixture and stir with a fork until a soft dough forms.
Turn out dough onto a lightly floured surface and give 10 to 12 kneads. Cut dough in half. Knead each half briefly into a ball; turn smooth side up and pat into a 6-inch circle. Cut into 6 wedges, but do not separate wedges.
In a small bowl, beat the egg white with a fork until just broken up. Brush the top of each scone with egg white and sprinkle lightly with sugar. With a pancake turner, carefully transfer the two cut circles to an ungreased cookie sheet. If necessary, reshape circle so that the 6 wedges in each are touching. (This will keep the raisins from burning.)
Bake 18 to 22 minutes, until medium brown. Cool on a wire rack; after 5 minutes pull the wedges apart and cover loosely with a dish towel.
Note: Egg white and sugar can be added before freezing the unbaked scones.